Some e2e util functions are not generating unique numbers properly

[shaominchen]

The following util functions are buggy:

1. GetVolumeNameWithTimeStamp
2. GetContainerNameWithTimeStamp
3. GetServiceNameWithTimeStamp

The intention of these functions is to generate a unique name, but we are using time.Now().Unix() which generates a number based on the same timestamp in seconds. The generated number will not be unique if we call this function multiple times in a short period or from different goroutines. It won't work even if we change it to time.Now().UnixNano().

We should fix these functions to use random number generator.

[shuklanirdesh82]

yeah @govint pointed out today #1310 (comment)

[ashahi1]

I know, its a trivial issue and I will take care of it.

[ashahi1]

Fixing it in PR #1385